Man has not been able to tell definitely just what the greatest depth of the ocean is, because it would be a practically unending task to go over every bit of it to take measurements. A great many exploring expeditions have been sent out to determine that interesting information so far as possible, however, and one of these, the Murray-Challenger expedition, has reported that the greatest depth that could be found in the Atlantic Ocean is 27,366 feet, in the Pacific Ocean 30,000 feet, in the Indian Ocean 18,582 feet, in the Southern Ocean 25,200 feet and in the Arctic Ocean 9,000 feet. They also stated that the Atlantic Ocean has an area in square miles, of 24,536,000; the Pacific Ocean, 50,309,000; the Indian Ocean, 17,084,000; the Southern Ocean, 30,592,000 and the Arctic Ocean, 4,781,000.